Loud-speaker



Oct. 29, 1963 M, L. PRIC 3,109,072

LOUD-SPEAKER Filed Sept. 26, 1960 l6 A/OA/ MAG/V5776 J A? INVENTOR.

MARLIN L. Pmce BY United States Patent 3,109,072 LOUD-SPEAKER Marlin L.Price, Huntington, Ind, assignor to Utah Radio Products Corporation,Huntington, Ind., a corporation Filed Sept. 26, 1960, Ser. No. 58,372 2Claims. (Cl. 179-1155) The present invention relates generally to aloudspeaker structure, and more particularly to a new and and improvedloud-speaker structure of the inverted permanent magnet type whichutilizes a novel integral core tip and coupling piece.

As is known, prior magnetic type loud-speakers each generally utilized aseparable core tip and coupling piece, typically secured together bybolt means, for example. Such a relationship resulted in added assemblyoperations, as well as increased costs for the finished loudspeaker, duenot only to the aforesaid added assembly time, but also to the requiredadditional part.

Accordingly, and by virtue of the instant invention, the applicant hasprovided a new and novel loud-speaker structure having a magneticcircuit which includes an integral core tip and coupling piece, thelatte-r affording efficient energy transfer during use, as well as caseand simplicity during the assembly operation. More specifically, theapplicant has provided a new and novel coupling device for a permanentmagnet type loud-speaker which is 100% iron at the end thereof adjacentthe magnet of the loud-speaker and. 100% brass or aluminum at the endthereof adjacent the basket of the loud-speaker, the latter serving asan insulator to thereby isolate the magnetic circuit from the metalbasket.

In addition, the arrangement of the instant invention permits readyassembly of the loud-speaker, as, for example, through the pro-alignmentof the con-e, the voice coil and spider assembly with reference to themagnetic circuitry of the loud-speaker. Moreover, by reason of theinvented relationship of the loud-speaker, ie. where the magneticstructure is disposed within the speaker basket, the finished unit has aminimum depth and may be mounted in areas heretofore found impossiblefor effective loud-speaker positioning.

Accordingly, the principal object of the present invention is to providea new and novel invented permanent magnet type loud-speaker structure.

Another object of the present invention is to provide a new and improvedloud-speaker structure utilizing a novel integral core tip and couplingpiece defined by a maximum disposition of iron at one end thereof and amaximum disposition of brass and/or aluminum at its opposite end.

A further and more general object of the present invention is to providea new and novel permanent magnet type loud-speaker structure whichpermits the preassembly and the pre-alignment of its components, andwhich, at the same time, has an inverted relationship whereby theassembled speaker has a minimum depth, while at the same timemaintaining effective electrical characteristics.

Other objects and a better understanding of the invention will becomemore apparent from the following description, taken in conjunction withthe accompanying drawing, wherein FIG. 1 is a view in front elevationshowing a loudspeaker formed in accordance with the instant invention;and,

FIG. 2 is an enlarged view in vertical section, taken at line 22 of FIG.1 of the invention and looking in a direction of the arrows, showingdetails of the applicants novel loud-speaker structure.

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made 3,109,072! Patented Oct. 29, 1963illustrated therein being contemplated as would normally occur to oneskilled in the art to which the invention relates.

Referring now to the figures, the applicants new and novel loud-speakerstructure :10 typically comprises a spider 12 through which a unitary orintegral core tip and coupling piece 14 is disposed, the latter to bediscussed in detail herebelow. A basket 15, typically made from metal,is positioned behind the spider 12 and is received in a groove 14afor-med in the rear surface of the integral core tip and coupling piece14. A cone 16 is conventionally disposed within the basket 15 by meansof a gasket 18, in a manner commonly known in the trade.

A permanent magnet 20 is disposed at one end of the integral core tipand coupling piece 14, with a pot 21 being disposed about the aforesaidpermanent magnet 20. The integral core tip and coupling piece 14, thepermanent magnet 20 and the pct 21 are secured together in operativerelationship by means of a nonmagnetic screw 24 which extends throughcored openings in the peranent magnet 20 and the pot 21 into a threadedopening in the integral core tip and coupling piece 14. As should beevident from FIG. 2, the pot 21 has a washer 25 disposed about the innerperiphery of the open end thereof, with a magnetic gap being providedbetween the pot 21 and the integral core tip and coupling piece 14.Magnet 20 has a base portion of relatively large diameter and a portion22 of lesser diameter adjacent the magnetic gap, thereby to improveefficiency by reducing flux leakage without material reduction of totaluseful flux. A voice coil 26 is disposed in the magnetic gap and aroundthe integral core tip and coupling piece 14, with leads 26a extendingtherefrom to a terminal board 30 positioned on the outer surface of thebasket 15. It should be understood, of course, that the terminal board30 provides the necessary means for connecting the loud-speaker 10 withan audio amplifier found in the overall sound reproduction system.

Referring again to the novel integral core tip and coupling piece 14which forms an important feature of the instant invention, such couplingdevice is a sintered part formed by infiltering brass or aluminum withpure iron in the sintering process, resulting in a coupling piece .whichis substantially iron at its end adjacent to the permanent magnet 20,and substantially 100% brass or aluminum at its end adjacent to themetal basket 15. Such material disposition is important, in that theoptimum amount of iron at the end of the integral core tip and couplingpiece 14 adjacent the magnet 20 becomes part of the magnetic circuit,and affords efficient energy transfer characteristics during the use ofthe loud-speaker. On the other hand, the optimum amount of brass oraluminum at the opposite end of the integral core tip and coupling piece14 serves as an insulator, thereby isolating the magnetic circuit fromthe metal basket 15.

The instant loud-speaker structure 10 is susceptible to ease in theassembly thereof, particularly inasmuch as the number of components hasbeen reduced with the use of the new and novel integral core tip andcoupling piece 14, thereby resulting in a faster assembly operation. Inaddition, the novel relation of components of the loudspeaker permitsfree movement of the voice coil 26 through the magnetic gap without thenecessity of specialized production line fixtures to insure centering ofthe permanent magnet 20 and the pct 21. The actual assembling istypically accomplished by first aligning the metal parts, i.e. thebasket 15 and the integral core tip and coupling piece 14; pre-aligningthe cone 16, the voice coil 26 and the spider 12, and placing suchstructure on the integral core tip and coupling piece 14; and, thenassembling the magnetic circuitry, principally defined by the magnet 20and the pot 21, through screw means 24.

From the preceding, it should be apparent that the applicant hasprovided a new and improved permanent magnet type loud-speaker structureutilizing a novel integral core tip and coupling piece which afiordsefficient energy characteristics during the use of the loud-speaker andwhich, at the same time, permits effective loudspeaker assembly.Moreover, being an inverted type speaker, a versatility factor ispresent for excellent usage thereof in various speaker applications.

The aforedescribed loud-speaker structure is, of course, susceptible tochanges within the spirit of the invention as, for example, changes ofdimensioning as well as a configuration of the various parts forming theassembled structure. The above description, therefore, should beconsidered illustrative and not as limiting the scope of the followingclaims.

I claim:

1. In an inverted loud-speaker structure, a basket having a centralportion with an aperture therein, an integral cylindrical core tip andcoupling piece, a permanent magnet and a pot, said basket, said integralcore tip and coupling piece, said permanent magnet and said pot beingsecured together, and said integral core tip and coupling piece being asintered part having one end of magnetic material engaging a portion ofsaid permanent magnet and an opposite end of non-magnetic materialprojecting through said aperture and engaging the front and rear facesof said central portion around said aperture to secure said integralcore tip and coupling piece to said basket, said pot having an open endportion disposed radially outwardly from said one end of said integralcore tip and coupling piece to provide a magnetic gap between said potand said integral piece, said permanent magnet having a base portion ofrelatively large diameter, and the said portion of said magnet whichengages said integral core tip and coupling piece being of a diametersmaller than said base portion and smaller than said one end of saidintegral core tip and coupling piece to minimize flux leakage, and avoice coil located radially outwardly of said integral piece andradially inwardly of said unitary core tip and coupling piece at an endproximate 7 said basket is substantially non-magnetic material.

References Cited in the file of this patent UNITED STATES PATENTS2,423,037 Marquis et al. June 24, 1947 FOREIGN PATENTS 983,550 FranceFeb. 14, 1951 59,536 France Feb. 3, 1954 (Addition to No. 965,754)

OTHER REFERENCES Electronic Technician, page 48, July 1960.

1. IN AN INVERTED LOUD-SPEAKER STRUCTURE, A BASKET HAVING A CENTRALPORTION WITH AN APERTURE THEREIN, AN INTEGRAL CYLINDRICAL CORE TIP ANDCOUPLING PIECE, A PERMANENT MAGNET AND A POT, SAID BASKET, SAID INTEGRALCORE TIP AND COUPLING PIECE, SAID PERMANENT MAGNET AND SAID POT BEINGSECURED TOGETHER, AND SAID INTEGRAL CORE TIP AND COUPLING PIECE BEING ASINTERED PART HAVING ONE END OF MAGNETIC MATERIAL ENGAGING A PORTION OFSAID PERMANENT MAGNET AND AN OPPOSITE END OF NON-MAGNETIC MATERIALPROJECTING THROUGH SAID APERTURE AND ENGAGING THE FRONT AND REAR FACESOF SAID CENTRAL PORTION AROUND SAID APERTURE TO SAID SECURE SAIDINTEGRAL CORE TIP AND COUPLING PIECE TO SAID BASKET, SAID POT HAVING ANOPEN END PORTION DISPOSED RADIALLY OUTWARDLY FROPM SAID ONE END OF SAIDINTEGRAL CORE TIP AND COUPLING PIECE TO PROVIDE A MAGNETIC GAP BETWEENSAID POT AND SAID INTEGRAL PIECE, SAID PERMANENT MAGNET HAVING A BASEPORTION OF RELATIVELY LARGE DIAMETER, AND THE SAID PORTION OF SAIDMAGNET WHICH ENGAGES SAID INTEGRAL CORE TIP AND COUPLING PIECE BEING OFA DIAMETER SMALLER THAN SAID BASE PORTION AND SMALLER THAN SAID ONE ENDOF SAID INTEGRAL CORE TIP AND COUPLING PIECE TO MINIMIZE FLUX LEAKAGE,AND A VOICE COIL LOCATED RADIALLY OUTWARDLY OF SAID INTEGRAL PIECE ANDRADIALLY INWARDLY OF SAID POT END IN THE MAGNETIC GAP.